Filesystem Cache is throwing TypeError: Cannot read property 'length' of undefined from ResolverCachePlugin

Bug report

What is the current behavior?

Attempting to get the cache working for webpack 5. I have it working on one of my local repos, but this one (a clone of a different website), is throwing an error:

Relevant config:

  cache: {
    type: 'filesystem',
    buildDependencies: {
      config: [ '/Users/xxx/public-web/config/webpack.config.js' ]
    }
  }

Throws this error:

(node:23491) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'length' of undefined
    at getType (/Users/xxx/public-web/node_modules/enhanced-resolve/lib/util/path.js:41:12)
    at Resolver.isPrivate (/Users/xxx/public-web/node_modules/enhanced-resolve/lib/Resolver.js:446:10)
    at Resolver.parse (/Users/xxx/public-web/node_modules/enhanced-resolve/lib/Resolver.js:430:25)
    at /Users/xxx/public-web/node_modules/enhanced-resolve/lib/ParsePlugin.js:33:29
    at _next0 (eval at create (/Users/xxx/public-web/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:8:1)
    at eval (eval at create (/Users/xxx/public-web/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:30:1)
    at /Users/xxx/public-web/node_modules/webpack/lib/cache/ResolverCachePlugin.js:199:17
    at Hook.eval [as callAsync] (eval at create (/Users/xxx/public-web/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:22:1)
    at Resolver.doResolve (/Users/xxx/public-web/node_modules/enhanced-resolve/lib/Resolver.js:398:16)
    at doRealResolve (/Users/xxx/public-web/node_modules/webpack/lib/cache/ResolverCachePlugin.js:138:13)

Setting the webpack config config: false eliminates the error and the build runs normally.

If the current behavior is a bug, please provide the steps to reproduce.

I see directories being created under my working repo in the node_modules/.cache folder, but not on my problem repo. A .cache folder is created, but no webpack or webpack/client-development folders.

What is the expected behavior?

Cannot figure out why one repo is throwing this error and the other is not.

Other relevant information: webpack version: 5.0.0 Node.js version: 14.13.1 Operating System: MacOS Catalina 10.15.7 Additional tools:

[alexander-akait]

@egs33 big thanks, found the problem

[alexander-akait]

Yes, I found bug, two problems:

• bug in sass-loader
• ugly error from webpack when you run:

const resolve = loaderContext.getResolve(options); 

resolve(context,  undefined);
// or resolve(undefined,  undefined)

WIP on first

---

I even can tell you why there is an error with node-sass and no problems with sass 😄